The subject embodiments of the invention relate to superconducting devices, and more specifically, to quantum interference devices and methods of fabricating the same. Superconducting quantum interference devices are utilized heavily in superconducting circuits. However, the superconducting quantum interference devices have large footprints due to a size of a loop area. Further, superconducting quantum interference devices can only detect fields orthogonal to the loop, which may be limiting for some circuits, especially if the loops are laid out on the substrate plane.
For example, Zagoskin et al. (U.S. Pat. No. 6,979,836) discusses “[a] superconducting structure that can operate, for example, as a qubit or a superconducting switch.” See Abstract. Zagoskin et al. also discusses that a “junction [ ] is preferably a grain boundary junction”. See, for example, column 11, line 62. In addition, Zagoskin et al. discusses “ . . . a grain boundary junction, such as [a] junction [ ] between two unconventional superconductors . . . ” See column 13, lines 9-11. In Zagoskin et al., an insulating material is “aluminum oxide (Al2O3) and silicon dioxide (SiO2).” See column 16, lines 60 and 61. However, aluminum oxide and silicon dioxide insulators cannot provide adequate performance for quantum computing applications because of the low loss requirements. Further, unconventional superconductors contribute to additional costs and fabrication complexity.